nova-next: Drop NOVA_USE_SERVICE_TOKEN as it is now True by default
nova-next: Drop NOVA_USE_SERVICE_TOKEN as it is now True by default

Change-Id: I68f7b7e78cc8a7f22f3e495b1b20a311dacff6c5
Depends-On: https://review.opendev.org/c/openstack/devstack/+/775573

openstack/nova,openstack/nova,mahak/nova,mahak/nova,openstack/nova,mahak/nova